decrypting ROT13 (vectors)

[wtd]

You can't turn a std::string into a character array? Someobody should tell the C++ standards committee.

code:

std::string foo = "hello"; char *bar = foo.c_str();

But you don't need this to deal with this problem.

[Geminias]

i dont know how. i intend to learn c++ inside and out, but there are just other things in my life so its taking a lot longer than i'd have wanted. plus i'm new to the whole concept of programming... i first understood what a string was just 2 weeks into september of last year.

So go easy on me... and i think the only other way i would have known how to do this would be to read all the information into an array, a big array, and then deal with it from there, but i wanted to try out vectors so i could learn them. and this experience has taught me a lot about vectors, which i wouldn't trade for anything. So to complete this experience it would be nice to be able to do this using the structure i already have. I will do it, with or without your help.

[Geminias]

code:

std::string foo = "hello"; char *bar = foo.c_str();

this code will not compile. Invalid conversion from a constant char to a char.[/code]

[wtd]

Once you have that function, you can use std::transform to rot13 every character in the file.

[Geminias]

i dont know what your talking about

[wtd]

Contemplate.

code:

#include <iostream> #include <vector> #include <fstream> #include <iterator> using namespace std; char rot13(char input); int main() {    ifstream file("file.txt");    vector<char> transformed_chars;    transform(istream_iterator<char>(file),              istream_iterator<char>(),              back_inserter(transformed_chars),              rot13);    copy(transformed_chars.begin(),         transformed_chars.end(),         ostream_iterator<char>(cout, "\n"));    return 0; } char rot13(char input) {    if (input >= 'a' && input <= 'z')    {       return input + 32;    }    else if (input >= 'A' && input <= 'Z')    {       return input - 32;    }    else    {       return input;    } }

[wtd]

Geminias wrote:

i narrowed down my largest problem to the fact that this:

code:

char word [] = *iWords_beg;

is an illegal initializer.

iWords_beg is not only a really bad variable name, but it's also an iterator. When you "dereference" is with *, you get a string. Not a pointer to a string. Further, this is a std::string, rather than a char array.

This examplains a lot of your other misconceptions.

Geminias wrote:

heres my code so far, and i didn't use templates because dont you have to make a struct or a class to implement them?

No, you do not. A function can be a template.

[Geminias]

c++:

#include <iostream> #include <vector> #include <fstream> #include <iterator> using namespace std; char rot13(char input); int main() {    ifstream file("fuck2.txt");    vector<char> transformed_chars;    transform(istream_iterator<char>(file),              istream_iterator<char>(),              back_inserter(transformed_chars),              rot13);    copy(transformed_chars.begin(),         transformed_chars.end(),         ostream_iterator<char>(cout, "\n"));    return 0; } char rot13(char input) {    if (input <= 'm' || A <= input && M >= input )    {       return input + 13;    }    else if (input >= 'm' && input <= 'z')    {       return ((input % 77) + 64);    }    else if (input >= 'M' && input <= 'Z')    {       return ((input % 109) + 96);    else    {       return input;    } }

code:

fuck.cpp:16: error: invalid initializer fuck.cpp:18: error: `int' is not a template fuck.cpp:18: error: missing `>' to terminate the template argument list fuck.cpp:18: error: expected primary-expression before "int" fuck.cpp:18: error: expected `;' before "int" fuck.cpp:18: error: expected primary-expression before "int" fuck.cpp:18: error: expected `)' before "int" fuck.cpp:18: error: declaration does not declare anything fuck.cpp:18: error: name lookup of `s' changed for new ISO `for' scoping fuck.cpp:18: error:   using obsolete binding at `s' fuck.cpp:18: error: expected `;' before ')' token

is my compiler not fully equipped with the stl? keep in mind i'm not using gcc right now.

[Geminias]

never mind i found the errors, it compiles now it just doesn't work lol.

[wtd]

Are you using VC++ 6?

[Geminias]

no, mingw. it works now, all is well... now i'll have to research those functions you gave me.

part, well actually, the biggest problem i have is i can't find the source of "stl::copy ()" or "stl::sort ()" and without it i found it difficult to pass the iterators into my decrypt function and manipulate the vector. partly because as you saw i had to guess what type they were, (the iterators) .

one question: how do i keep spaces? i found that this program eliminates the spaces in its output... how would i keep them?

[wtd]

Yes, that has to do with the default way istreams work. I had failed to take this into account.

As for figuring out how functions like copy and transorm work:

http://www.sgi.com/tech/stl/

It's all there. The place to start would be the table of contents.

[wtd]

Oh, and with MinGW you are using G++. Minimalist GNU for Windows.

[Geminias]

oh, lol. yeah it wasn't the compiler after all.

[wtd]

My rot13 function's body was also all wrong. My brain is apparently having some issues. Still, my advice about the general stuff... dead on.